Problem: $ { {3} \times \left[\begin{array}{rrr}{-1} & {-1} & {3} \\ {3} & {-1} & {1}\end{array}\right] = {?} } $
Solution: To multiply a matrix by a number, multiply each item of the matrix by the number. ${\left[\begin{array}{rrr}{3}\times{-1} & {3}\times{-1} & {3}\times{3} \\ {3}\times{3} & {3}\times{-1} & {3}\times{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rrr}{-3} & {-3} & {9} \\ {9} & {-3} & {3}\end{array}\right]}$